A functional group in organic chemistry is a moiety in a molecule that produces the molecule’s characteristic chemical reactions. The same functional group will undergo the same chemical modifications, despite the remaining structure of the molecule. It enables the systematic study of chemical processes and the actions of chemical substances and chemical synthesis growth. Other neighbouring functional groups may change a functional group’s reactivity.
There are many tests for functional group analysis in chemistry, including the test for alcoholic group, amino group, test for saturation and unsaturation group, test for aldehyde and ketone groups, etc. For example, Iodoform test is performed to check the presence of an alcohol group, and bromine water test is to identify the unsaturated group in the molecule, and so on.
Test to identify various functional groups
Organic chemistry is the branch of chemistry dealing with the structure, behaviours and reactions of substances containing carbon. In organic chemistry, the objects of study are:
- Compounds containing hydrogen and carbon.
- Structures dependent on carbon and including other elements.
Functional groups are referred to as atoms or groups of atoms which substitute hydrogen atoms in hydrocarbons. These can be -COOH, -OH, -CHO, -CO, -COOR, -COCl and -Cl. Functional groups are responsible for a molecule’s characteristics.
Tests for -COOH (Carboxylic group)
Organic substances comprising the carboxyl functional group are referred to as carboxylic acids. Two types of carboxylic acids are
- Aliphatic carboxylic acid
- Aromatic carboxylic acid
In water, aliphatic acids are soluble, whereas aromatic carboxylic acids are sparingly soluble.
List of a test to identify -COOH group
- Sodium Hydrogen Carbonate Test
- Litmus Test
- Ester Test
Tests for -OH (Alcoholic Group)
Alcohols are compounds in which the -OH group is bound to an aliphatic chain or an organic compound’s side chain. Alcohols are known as monohydric alcohol containing only one OH group, dihydric alcohol containing two OH groups and trihydric alcohol containing three OH groups, based on the quantity of the hydroxyl group in the molecule.
List of a test to identify -OH group
- Sodium metal test
- Ceric ammonium nitrate test
- Acetyl chloride test
- Iodoform test
Tests for -CHO and -CO (Aldehyde & Ketone Groups)
The compounds forming the carbonyl group are ketones and aldehydes. The carbonyl carbon is bound in Aldehydes to at least one hydrogen atom and to a carbon comprising the aromatic or aliphatic group, except in formaldehyde. In ketones, two aromatic or aliphatic groups are attached to the carbonyl carbon.
List of a test to identify -CHO and -CO group
- 2,4-DNP test
- Sodium bisulphite test
- Tollen’s Test
- Schiff’s Test
- Sodium nitroprusside Test
Tests for unsaturation
Saturated hydrocarbons are hydrocarbons which include a single bond between carbon atoms. They may have the framework of a branch, ring structure or straight chain. Hydrocarbons involving triple or double bonds between two carbon atoms are termed as unsaturated hydrocarbons.
List of a test to identify an unsaturated group
- Alkaline KMnO4 Test or Baeyer’s Test
- Bromine water Test
We should understand the dangers of specific chemicals before conducting any test. For example, if a person performs a bromine water test, then he should know what are the hazards of using bromine water and should take the safety measurement.
Functional groups are unique atom groupings within molecules that will have their structural features irrespective of the other atoms present in a compound. Amines, alcohols, carboxylic acids, ethers, aldehydes and ketones are a few examples.